Charge forming device



Aprll 19, 1932. F. E. ASELTINE CHARGE FORMING DEVICE Filed June 20, 1928 Patented Apr. 19, 1932 UNITED STATES PATENT OFFICE FRED E. ASELTINE, OF DAYTON, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO DELCO Y PRODUCTS OOBIPORATION, F DAYTON, OHIO, A CORPORATION OF DELAWARE CHARGE FORMTNG DEVICE Application led June 20,

This invention relates to charge forming devices for internal combust" on engines, more particularly Ato such devices which are provided with a plurality of primary mixing chambers, each of which is adapted to supply a primary mixture of fuel and air to one of a plurality of secondary mixing chambers located adjacent the engine'intake ports and in which additional air may be mixed r with the primary mixture under certain operating conditions.

An example of a charge forming device of this character is shown in the copending application of F. E. Aseltine et al., Serial No.

221,371, tiled September 22, 1927, which matured to patent 1,819,495 granted Aug. 18, 1931.

It is an object of the present invention to provide simplified and improved means for controlling the mixture proportions which shall be effective to form a mixture having the proportions of fuel and air which will most satisfactorily operate the engine under all possible operating conditions.

It is aI further object of this invention to provide means for controlling the iow of fuel in accordance with the engine speed, and manifold suction, and which may be designed to produce a mixture of any desired proportions under varying conditions of speed and load.

According to the present invention these objects are accomplished by the provision of al collapsible bellows connected to the manifold between the throttle and the engine by a suction connection and connected by a link to a cam, which operates a fuel valve through an intermediary lever and is so contoured that the valve is opened as the lmanifold. suction falls onv opening of the throttle to increase the engine speed,vor on increase of load with a fixed throttle opening. While the cam is preferably contoured to maintain the mixture proportions substantially vconstant on changes of speed due to-changes in throttle position it may be designed to give a mixture richer or leaner than normal at any point in the entire speed range of the engine: for instance the cam may be so shaped as to give a sudden increase 'in fuel flow at high speed, 5 say that corresponding to a vehicular speed 1928. Serial No. 286,976.

of 45-50 miles per hour on the level in-order to give the desired power for high speed operation. Further the cam is designed to give a richer mixture on increase of load with iixed c throttle.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying. drawings, wherein a preferred form of embodiment of the presu ent invention is clearly shown.

In the drawings:

Fig. 1 is a vertical, longitudinal section through the carburetor unit and the middle outlet branch of the manifold.

Fig. 2 is a vertical lateral section on the line 2 2 of Fig. 1.

The device disclosed herein comprises a main air manifold indicated in its entirety by the reference numeral 10 and having three outlet branches the middle one of which 12 is shown herein. Each of these branches communicates with one of the intake ports 14 of an internal combustion engine, each of which serves two adjacent cylinders as disclosed in the copending applications above referred to. Each of the manifold branches is provided with an attaching .flange 16 for attaching the manifold tothe engine block in the usual way, and a {iange 18, to which the carburetor unit mav be secured is provided adjacent the manifold inlet.

The carburetor unit comprises a main housing 2O having an. attaching flange 22 secured by screws 24 to the flange 18. Anv air inlet horn 26 is secured by screws 28 to the main housing and communicates with an opening in the top wall of said housing. 'A

casting 30 having'` certain fuel passages and a dash pot cylinder formed therein is secured by screws 32 to the bottom of the main housing. and a sheet metal fuel bowl 34 is held tight against an annular shoulder 36 formed on a skirt 38 depending from the'main housing by a screw 40 screwed into the casting 30, a suitable gasket being provided to prevent leakage around the screw.

Fuel is conducted from a main source 0"? supply to the fuel bowland the flow is controlled by a float (not shown) in the usual 100 I casting 30 and cooperates with a seat 52 formed where the passage 44 joins the bore 50. This valve is controlled by mechanism described hereinafter, to regulate the proportions of fuel and air in the mixture as desired. The passage 44 connects with a horizontal fuel' canal 54 at its upper end and said canal communicates with three pairs of calibrated low and high speed jets or plugs 56 and 58 respectively, each of these pairs of jets being adapted to convey fuel to one of the mixture passages 42 in a manner later described.

Fuel is lifted from the fuel bowl to the primary mixture passages by the suction therein. When the throttle is moved toward closed position to reduce the engine speed this suction may be reduced sufficiently to allow the fuel column between the bowl and the jets to drop enough to temporarily starve the engine unless means were provided to prevent this action. To prevent this action a check v'alve60 is provided, which is normally lifted above an annular rim 62, surrounding the outlet of passage 44, by the suction, but on reduction of suction immediately seats on said rim preventing downward flow through the passage 44. A two stage metering Evalve 64 of the type'shown in the above mentioned applications and operating in the same Way, is provided in the passage 44.

The primary mixture passages 42 to which the pairs of jets 56 and 58 deliverfuel are bored horizontally through the central part of the main housing 20, are parallel to each other and relatively close together as indicated in the drawings. Air is admitted to each of the primary mixture passages through an air inlet bushing 66 screwed' into the outer end of the primary mixture passage.- Immediately posterior to said bushing a small Venturi tube 68 is received iny an enlargement 70 of the primary mixture passage. Rash of the Venturi tubes is provided with two -external ribs 72 arranged circumferentially of the tube and fitting tightly in the enlargement 70. These ribs form between them a fuel channel 74 with which the low speed jet 56 communicates, and a series of orifices 76 are provided in theVenturi tube to connect the interior of the tube with the said channel. The Venturi tube 68 is reduced in size at its inner end and is spaced from the wall of the mixture passage as shown in Fig. 1. This space 78 is substantiallyA a dead air space in which the suction or partial vacuum is substantially the same as that maintained in the mixture passage between the end of the Venturi tube and the throttle, which controls flow through the mixture passage and is more fully described hereinafter. Each main fuel nozzle 58 terminates in the Wall of the mixture passage 42 with which it is A associated at a point opposite the reduced inner end of the venturi so that fuel flows therefrom into the space 78 and the suction in said space controls the flow of fuel. It will be clear that the suction within the Venturi tube 68, which is eective to cause a flow of fuel through the low speed jet 56 and orifices 76 communicating therewith, is greater than that effective to cause a flow through the jet 58. Hence each jet 56 is effective to supply fuel to its associated mixture passage at low speed when the suction in the mixture passage is relatively low while the main or high speed jet supplies no fuel until a higherengine speed has been reached. .The jets 56, therefore, are effective to supply fuel to the mixture passages at all speeds and under all operating conditions, supplying all of the fuel for idling and low speed operation and a part of the fuel at all other times, while the main or high speed jets are not effective to supply any fuel to the mixture passages until the engine is running at a speed corresponding substantially to a vehicular speed of 20-.25 miles per hour for example. Thel operation and construct-ion of the fuel jets is more fully described in my copending application Serial No. 288,684, filed June 27, 1928, in which such structure is claimed.

The flow of the primary mixture through the passages 42 is controlled by a single throttle valve 80 which extends across all of the passages 42 and has grooves 82 therein which register with said passages. The means for operating this throttle forms no part of the present invention but is fully disclosed in the said patent 1,819,495. Each primary mixture passage communicate-s with a pipe associated with each branchof the manifold for conveying the primary mixture to the secondary mixing chambers. The pipe 84 associated with the middle outlet branch 12 of the manifold is shown herein and those which convey primary mixture to the other branches of the manifold are fully shown and described in the above mentioned applications, such structure forming no part of the present invention.

All of the air which is mixed with the primary mixture in the secondary carburetors is admitted through the air horn 26, the tiow being controlled by an air vlave 86 normally held against a seat 88 by a spring 90. Air passing the valve iiows Vfirst into an air chainber 92 and thence through a secondary air passage 94 communicating with the inlet end of the air manifold and provided with a throttle valve 96 secured to a shaft 98 journalled in the housing 20, and Operated in a manner brieliy described hereinafter to reguholding the air valve closed. To preventI sufficient opening of the air valve to cause leaning of the mixture and to prevent Hutter-v ing of said valve a dash pot 106 is provided which maybe. of the form shown in either 'of the copending cases referred to or may be of any conventional or desired design.

The throttle operating mechanism forms no part of this invention and is not shown herein, but for-fthe purpose of facilitatingunderstanding of the operation of the whole device the mode of operation of the. throttles 80 and 96 will be very briefly described.

During operation at "all speeds uppto a vehicular speed of 20-25 miles per hourl it is desirable that the primary mixture passages supply all the combustible mixture to the engineU lcylinder, and at speeds higher than that to admit air to the secondary mixing chambers Athrough the passage 94. To secure this result the two throttles 80 and 96'are provided with a common operating mechanism so arranged that the primary throttle 80 is given a predetermined movement before the throttlfel 96 begins to open and after said throttle 80 begins to open both throttles move together to wide lopenposition.`

` There are threel secondary mixing chambers of identical construction, each of which comprises a Venturi tube 110 secured' in anV outlet branch of the manifold in such `position that its point of greatest depression is immediately adjacent the outlet end of the.`

primar mixture pipe associated with that particu ar manifold branch, as shown in Fig. 1.. Each venturiis provided with an external circumferential rib 112 which, when the device is assembled, is adapted to be clamped f between shoulders 114 and 116 on the manifold and engine block respectively. 4The Venturi tubes cause the air passing the ends of the primary mixture delivery pipes to rnove at high, velocity creating in each tube a high suction during all operating conditions.

rlhe novel means to control the flowl of fuel through the passage 44 in accordance with the engine suction andspeed will now be de.` scribed. The tapered fuel valve 48 previously described is provided atfits upper end with a flat extension 120 which is received between the two arms 122 of a bifurcated lever 124 pivoted at 126 in a support 128 depending from the housing 20, the valve being connected to the lever by a pin 130, received in slots 132` in the arms 122. roller 134 is rotatably mounted on the other end of lever 124 and is engaged by a cam 136, operated in a manner later described, to open the fuel valve which is normally held closed by a spring 138 connected to the lever 124 and a bracket 140 projecting from the housing 20. The bracket 140 also supports the cam 136 which is pivoted ona pin 142 projecting from the bracket, a nut 143 preventing lateral movement of the cam.

The cam is operated in accordance with l variations in suction in the manifold by means of an expansible metal bellows 144, of the type generally known as a sylphon, the upper end of which is secured to a supporting member 146 integral with and projecting from the housing 20 while the lower end of the bellows is free, permitting the bellows to expand and contract as the manifold suct1on varies, such suction being communicated to the bellows through a pipe 148 which is a union 150, one part of which is screwed into the manifold between the throttle 96 and the engine as shown in Fig. 1. Con- "connected to the manifold inlet vby means of nected with the lower end of the bellows and moving with the latter as it expands and contracts is a rod 152 guided in an adjustable sleeve or collar 154 screwed into a part of the supporting member 146 and provided lwith a krurled head 156 by means of which it may be adjusted. The lower end of the rod is connected by apin and slot connection- 158 to the cam 136' and a compression spring 160, received between the collar1 154 and a flange 162 secured to the rod at its lower end, tends to push the rod down and rotate the cam in a clockwise direction-in Fig-2. The rod will come to rest when the force of the spring' tending to lower the rod is balanced by the force of the manifold suction tending to lift the rod through the medium of the metal bellows. "By adjusting the collar 154 the force ofthe spring may be varied and hence the position of the cam at idling and other engine speeds may be varied, varying the amount of opening of the fuel valve at' idling and other engine speeds..

The operation ofthe above device will now Vbe described. -Letl` it be assumed that the engine is not operating.l There is no suction or partial vacuum in the manifold to oppose the action of spring 160 and said spring, being more powerful than spring 138 will rotate the cam 136 in a clockwise direction bringing the high point'of :the cam into engagement with the roller.` 134. and opening the fuel valve 48 against the tension o f spring sol 138. The engine suction at pointsposterior to the throttle 96 is highest when the carburetor is choked to start, or is ecperating at low speed with throttle 96 clos so that as soon as the engine is started and 1s operatlng at low speed the suctioncollapses the metal If, now, it be desired to increase the speed of the engine the throttle 80, or throttle 96, or both, are opened depending on whether the increase in speed is to be great or small,

and on increase of speed it is desirable to increase the amount of fuel supplied to the mixture passages. On opening movement of either or both throttle valves the manifold suction which is communicatedv to the pipe 148 falls permitting expansion of the metal bellows 144 and a clockwise movement of the cam 136 which opens the valve against the tension of spring 138 until a condition of balance of the forces effective to move the cam 136 in opposite directions is reached. If either, or both the throttles .are open and a closing movement of one or both takes place to reduce the speed the action is the reverse of that above described. The cam is moved counter clockwise by a contraction of the metal bellows to permit a closing movement of the fuel valve.

Changes 'in load with a constant throttle setting will effect changes in the suction maintained in the manifold and will` result in variable positioning the fuel valve in accordance with the load. For instance it may be assumed that an automobile is running on a level at 'any given speed, say 35 miles per hour. If an up grade is reached the load incombustion engine having infcombination a creases, the engine slows down and the manifold suction decreases as the engine speed decreased. The decrease in suction causes expansion of the. metal bellows and opening 'of the fuel valve as previously described, t0

form a richer mixture which is necessary to properly operate the engine on heavy load. If, on the other hand, the automobile reaches a down grade, the engine speed increases due to the lighter load, the manifold vacuum i11- creases and the metal bellows is collapsed to effect counter clockwise movement of the cam 136 and closing movement of the fuel valve.

other'forms might be adapted, all comingv within the scope of the claims which follow.

What is claimed is as follows: 1. A charge forming device for an internal mixture passage, means for supplying fuel and air thereto, a throttle, means for varying the amount of fuel in said mixture comprlsing a cam adapted to variably control the fuel admission as the cam is moved to different positions and means for moving the cam in accordance with variations in engine speed and load.

2. A charge forming device for an internal combustion engine having in combination a mixture passage, means for supplying fuel and air thereto, a throttle, a fuel valve for variably regulating the ow of fuel to the mixture passage, a cam for variably positioning thefuel valve as the cam is moved to different positions, and means for moving the cam in accordance with variations in engine 'speed and load.

3. A charge forming device for an internal combustlon engine having in combinatlon a mixture passage, means for supplying fuel and air thereto, a throttle, a fuel valve for variably regulating the flow of fuel'to the mixture passage, a cam for variably positioning the fuel valve, a pressure responsive device for operating the cam and means for communicating the pressure maintained within the mixture passage to said pressure responsive device.

4. A charge forming device for an internal combustion engine having in combination a mixture passage, means for supplying fuel and air thereto, a throttle, a fuel valve for regulating the flow of fuel to the mixture passage, a cam for variably positioning the fuel valve, a pressure responsive device for operating the cam and a suction passage connecting the pressure responsive device with the mixture passage at a point posterior tov the throttle.

5. A charge forming device for interna-1 combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a suction operated metering valve subject to the suction in the mixture passage anterior to the throttle for controlling the flow of fuel, and an additional fuel valve subject to` substantially the same Isuction as is maintained in the intake manifold.

6.'A charge forming device for internal combustion engines comprising a` plurality of primary mixture passages adapted to supply fuel air mixture to a plurality of secondary mixing chambers, means for supplying fuel andair to said primary mixture passages, a single secondary air passage supplying auxiliary air to all of the secondary mixture passages, and means for varying the flow of fuel to said primary mixing chambers in accordance with variations in suction in said secondary air passage.

7. A charge forming device for internal combustion engines comprising a mixture passage, an air inlet therefor, a plurality of fuel inlets therefor, a plurality of restrictions each of which is adapted to regulate the flow of fuel through one of said inlets, a fuel passage supplying fuel to all of said fuel inlets, a valve' for regulating the flow through said passage, a mixture throttle, an air throttle and means operated in accordance with the suction posterior to said air throttle for operat-ing said valve.

8. A charge forming device for internal combustion engines comprising a primary mixture passage, a fuel passage for supplying fuel and air thereto, a secondary mixing chamber into which the primary mixture passage delivers, a passage supplying air to the said secondary mixing chamber, means for controlling the flow through said fuel passage comprising a plurality of valves, one of which is subject to the suction in the primary mixture passage and the other of which is controlled by the suction in the passage supplyin air to the secondary mixing chamber.

charge forming device for internal combustion engines comprising a mixing` chamber, means for supplying fuel and air thereto, a secondary air passage supplying additional air, and means for regulating the flow of fuel to the mixing chamber, said means being controlled by the suction in the mixing chamber and in the secondary-air passage.

l0. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a secondary air passage supplying additional air, and a plurality of means for regulating the flow of fuel to the mixingl chamber, one of said means being controlled by the suction in the mixing chamber and the other of said means being subject to the suction in the auxiliary air passage.

11. Acharge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a mixture throttle controlling the How of mixture therethrough, a secondary air passage supplying additional air, an air throttle controlling the flow of `air therethrough, a fuel valve for regulating the iow of fuel to the mixture passage, and pressure responsive means for controlling the position of the fuel valve, said means being controlled solely by the suction in the secondary air -in the secondary air passage, means for varying the amount of fuel supplied to said mixture passage comprising'a pressure responsignature.

v FRED E. ASELTINE. 

